Question

Genetics help please!!Two mothers give birth to sons at the same time at a busy urban hospital. The son of mother 1 is afflicted with hemophilia, a disease caused by an X-linked recessive allele. Neither parent has the disease. Mother 2 has a normal son, despite the fact that the father has hemophilia. Several years later, couple 1 sues the hospital, claiming that these two newborns were swapped in the nursery following their birth. As a genetic counselor, you are called to testify.Part AWhat information can you provide the jury concerning the allegation?What information can you provide the jury concerning the allegation?Passage of X-linked genes typically occurs in a complicated way and the data available can neither support nor deny the first couple's claim.Passage of X-linked genes typically occurs from affected parent to affected son. The fact that neither parent from couple 1 has hemophilia suggests that their son could not have the condition. The first couple's claim is valid.Passage of X-linked genes typically occurs from affected father to affected son. The fact that the father in couple 2 has hemophilia would ensure his son to have this condition. The first couple's claim is valid.Passage of X-linked genes typically occurs from carrier mother to affected son. The fact that the father in couple 2 has hemophilia would not predispose his son to hemophilia. The first couple has no valid claim.

Answer 1

Answer:

If mother 1 is a carrier of hemophilia, it is likely that her son would in fact have hemophilia while the son of mother 2 does not. Mother 1 would have the genotype XᴴXʰ, meaning she has one recessive allele for hemophilia, while the father would have the genotype XᴴY, and would neither be afflicted with hemophilia nor carry it. If you do a punnett square, it shows that the son of mother 1 would have a 50% chance of having hemophilia, since he wouldn't have a second X chromosome with a dominant allele to mask the recessive hemophilia allele. Also, if mother 2 has the homozygous dominant genotype XᴴXᴴ despite the father having hemophilia and the genotype XʰY, a punnett square for this couple proves that their son would have a 0% chance of having hemophilia. Therefore, it is very likely that their sons were not switched at birth and the correct answer is D: The fact that the father in couple 2 has hemophilia would not predispose his son to hemophilia. The first couple has no valid claim. Hope this helped!